CN107406306B - Glass blank for press molding, glass optical element and method for producing the same - Google Patents

Abstract

The present invention provides a glass optical element, a glass material for press molding, and a method for manufacturing a glass optical element using the glass material for press molding, wherein the glass optical element comprises an oxide glass, a coating layer covering at least a part of the surface of the oxide glass, and an intermediate layer provided between the oxide glass and the coating layer, the coating layer is a metal oxide film having an oxygen deficiency in comparison with a stoichiometric composition, and in the intermediate layer, the diffusion rate of oxygen atoms contained in the oxide glass is higher than the diffusion rate of metal atoms contained in the metal oxide film at a temperature equal to or higher than the glass transition temperature of the oxide glass.

Description

Glass blank for press molding, glass optical element and method for producing the same

Cross-referencing of related applications

This application claims the priority of Japanese Patent Application No. 2015-73862 filed on March 31, 2015 and Japanese Patent Application No. 2015-243700 filed on December 15, 2015, the entire contents of which are specifically incorporated herein by reference. .

technical field

The present invention relates to a glass blank for press molding, a glass optical element, and a method for producing the same.

Background technique

As a method of manufacturing a glass optical element (hereinafter also referred to as "optical element") such as a glass lens, there is known a method in which a glass blank for press molding is press-molded with an upper mold and a lower mold having opposing molding surfaces. forming.

When molding an optical element by press molding, the glass blank for press molding and the molding surface of the molding die are in close contact with each other at a high temperature. Therefore, a chemical reaction occurs at the interface between them, resulting in hot sticking, blurring, and scratch-like reactions in some cases. marks, etc., thereby resulting in a decrease in the optical properties of the optical element obtained by compression molding.

Conventionally, as a means for preventing the occurrence of the above-mentioned reaction marks, it has been proposed to provide one or more layers of coatings on the surface of the glass blank for press molding to suppress the reaction between the molding die and the glass (for example, see Japanese Patent Laid-Open No. 2011-1259 ). (The entire contents of the description are specifically incorporated herein as a disclosure)).

SUMMARY OF THE INVENTION

However, as a result of research by the present inventors, in the production of glass optical elements by press molding, minute air bubbles are generated (foamed) in the glass after the press molding, resulting in a decrease in the homogeneity of the optical element. . In order to provide optical elements with higher optical properties, it is desirable to suppress foaming in glass.

Therefore, in order to find a means of suppressing foaming in glass, the present inventors intensively studied the cause of the generation of bubbles. As a result, an unexpected phenomenon was found in which even when press-molding was performed in a non-oxidizing atmosphere, air bubbles generated in the optical element after press-molding contained a large amount of oxygen. Since it is only oxide glass as a cause of generation of oxygen during press molding in a non-oxidizing atmosphere, it is considered that oxygen derived from oxide glass is involved in the generation of bubbles.

One aspect of the present invention provides means for suppressing generation of air bubbles in a press-molded glass optical element.

One aspect of the present invention relates to a glass blank for press molding, comprising:

oxide glass (hereinafter also referred to as "glass");

A coating layer covering at least a part of the surface of the oxide glass, the coating layer being a metal oxide film deficient in oxygen compared to the stoichiometric composition; and

an intermediate layer provided between the oxide glass and the coating layer,

In the intermediate layer, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the diffusion rate of oxygen atoms contained in the oxide glass is higher than the diffusion rate of metal atoms contained in the metal oxide film at the above temperature quick.

Another aspect of the present invention relates to a method for producing a glass optical element including a press-molding step of press-molding a glass blank for press-molding to form a press-molded body,

The said glass blank for press-molding is the glass blank for said press-molding.

Another aspect of the present invention relates to a glass optical element including:

oxide glass;

A coating layer covering at least a part of the surface of the oxide glass, the coating layer being a metal oxide film deficient in oxygen compared to the stoichiometric composition; and

an intermediate layer provided between the oxide glass and the coating layer,

In the intermediate layer, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the diffusion rate of oxygen atoms contained in the oxide glass is higher than the diffusion rate of metal atoms contained in the metal oxide film at the above temperature quick.

In order to suppress foaming in glass due to oxygen derived from oxide glass, the inventors of the present invention have conducted intensive studies. As a result, in a glass blank for press molding, the oxide glass is interposed with the above-mentioned intermediate layer. The above-mentioned coating layer is provided.

Although the coating layer is a metal oxide film, it is in a state deficient in oxygen compared with the stoichiometric composition. Therefore, if the stoichiometric composition in a more stable state is approached, it is in a state in which oxygen is easily accommodated. Therefore, as long as the metal oxide film is in this state, the oxygen generated in the glass during press molding and causing foaming can be contained, and the generation of bubbles can be suppressed.

However, during press molding, the metal atoms contained in the coating layer can also move (diffuse) from the coating layer to the oxide glass side. If the effective film thickness of the coating layer is reduced or the film disappears due to this diffusion, it is difficult to suppress the generation of air bubbles by the coating layer.

On the other hand, in the above-mentioned intermediate layer, at a temperature equal to or higher than the glass transition temperature of the above-mentioned oxide glass, the diffusion rate of oxygen atoms contained in the above-mentioned oxide glass is higher than that of the metal contained in the above-mentioned metal oxide film at the above-mentioned temperature. Atomic diffusion is fast. Thereby, the diffusion of oxygen atoms from the oxide glass (movement to the coating layer side) proceeds in preference to the diffusion of metal atoms from the coating layer. Therefore, the coating layer can efficiently accommodate oxygen atoms from the oxide glass to the coating layer without reducing the effective film thickness or disappearing the film, thereby suppressing the generation of air bubbles.

In addition, the optical element thus obtained has the above-mentioned coating layer and intermediate layer through the molding process. Since the coating layer contained in the optical element accommodates oxygen atoms diffused from the oxide glass during press molding, the content ratio of oxygen atoms to metal atoms is higher than that contained in the glass blank for press molding. However, in one form, the coating layer included in the optical element is still in a state deficient in oxygen compared with the stoichiometric composition, which is clarified from the research results of the present inventors.

According to one aspect of the present invention, it is possible to provide a method of manufacturing an optical element capable of suppressing generation of air bubbles in glass during press molding.

Furthermore, according to one aspect of the present invention, it is possible to provide a homogeneous optical element without generation of air bubbles.

Description of drawings

1 shows the diffusion rate (T1) of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass in the intermediate layer, and the metal atoms contained in the metal oxide film at the temperature. Model diagram of the relationship between the speed of diffusion (T2).

2 is a schematic cross-sectional view showing a glass blank for press molding according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a press molding apparatus.

4 is a graph showing the result of a depth-direction analysis of secondary ion strength by TOF-SIMS before press molding (glass blank for press molding) in Example 1. FIG.

FIG. 5 is a diagram showing the result of a depth-direction analysis of the secondary ion intensity by TOF-SIMS before press molding (glass blank for press molding) in Example 2. FIG.

Detailed ways

Hereinafter, the present invention will be described in further detail. Hereinafter, specific embodiments will be described with reference to the accompanying drawings, but the present invention is not limited to the embodiments shown in the accompanying drawings.

First, in the intermediate layer, the diffusion rate (T1) of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass and the diffusion rate of the metal atoms contained in the metal oxide film at the above temperature The relationship between the speed (T2) will be explained. In addition, the relationship between T1 and T2 means the relationship between T1 and T2 at the same temperature which is equal to or higher than the glass transition temperature of the above-mentioned oxide glass.

1 shows the diffusion rate (T1) of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass in the intermediate layer, and the metal atoms contained in the metal oxide film at the temperature. Model diagram of the relationship between the speed of diffusion (T2). In the above-mentioned glass blank for press molding, as shown in FIG. 1 , the oxide glass is in contact with the intermediate layer. In addition, the intermediate layer is in contact with the coating layer. As shown in this model diagram, in the intermediate layer, as long as the relationship of T1>T2 is satisfied, the diffusion of oxygen atoms from the oxide glass (movement to the coating layer side) proceeds in preference to the diffusion of metal atoms from the coating layer. As a result, the coating layer can efficiently remove oxygen atoms from oxidation without causing a decrease in the effective film thickness or disappearance of the film at a temperature that is generally performed for press molding and at a temperature equal to or higher than the glass transition temperature of the oxide glass. The object glass is contained in the coating layer to suppress the generation of air bubbles.

The present inventors considered the reason why bubbles can be suppressed from being generated inside the glass by press-molding using the above-described glass blank for press-molding. However, the above description includes the speculation of the present inventors, and the present invention is not limited by these speculations at all.

It should be noted that it can be confirmed that the intermediate layer satisfies the relationship of T1>T2 by the fact that no effective reduction in the film thickness of the coating layer or disappearance of the film occurs after compression molding.

Hereinafter, the above-mentioned glass blank for press molding (also referred to as a "preform" (PF)) will be further described in detail.

[Glass blank for press molding]

2 is a schematic cross-sectional view showing a glass blank for press molding according to an embodiment of the present invention. In FIG. 2, the glass blank PF for press molding for concave meniscus lenses is shown as an example.

The glass blank for press molding shown in FIG. 2 includes: an oxide glass 1; and a coating layer 3 that coats at least a part of the surface of the oxide glass 1, and the coating layer 3 is a metal oxide film deficient in oxygen compared to the stoichiometric composition ; and the intermediate layer 2 disposed between the oxide glass 1 and the cladding layer 3 . The coating layer 3 and the intermediate layer 2 only need to coat at least a part of the surface of the oxide glass 1 . That is, the oxide glass 1 may have a part of its surface that is not covered with the coating layer 3 and the uncoated portion of the intermediate layer 2, or may have the entire surface covered. In one embodiment, when a glass blank for press molding is press-molded to form a glass optical element, at least the portion of the oxide glass that forms the optically functional surface of the optical element may be coated. The optical functional surface means, for example, an area within an effective diameter of an optical element. However, since the coating layer 3 can accommodate oxygen atoms from the oxide glass as long as it exists in at least a part of any part of the surface of the glass material for press molding, it is not limited to the above-mentioned embodiment.

Next, the coating layer, the intermediate layer, and the oxide glass constituting the glass blank for press molding will be sequentially described.

<coating layer>

The coating layer of the coating oxide glass is a metal oxide film in a state deficient in oxygen compared to the stoichiometric composition. Therefore, the coating layer may be formed by a film formation method capable of forming the above-described metal oxide film. For example, on the surface of a glass block made of oxide glass, after forming an intermediate layer described later, using a metal (a simple substance of metal) as a target, in a non-oxidizing atmosphere by sputtering, vacuum evaporation, By forming a film by a known film-forming method such as CVD (Chemical Vapor Deposition), it is possible to form a metal oxide film that is deficient in oxygen compared to the stoichiometric composition. Here, the non-oxidizing atmosphere refers to an atmosphere composed of a gas other than oxygen such as an inert gas such as argon and nitrogen. However, oxygen derived from trace oxygen mixed in as an impurity, not actively, is allowed to exist in the atmospheric gas.

The lower limit of the film formation temperature (temperature of the glass block) is preferably 150°C or higher, and more preferably 200°C or higher. The upper limit is preferably less than the glass transition temperature of the oxide glass. The upper limit temperature is, for example, 450°C or lower.

Specifically, two or more oxide glasses with intermediate layers formed thereon are arranged in a tray, then placed in a vacuum chamber, and the vacuum chamber is evacuated, and the oxide glasses are heated to about 300 by a heater. ℃ temperature. After exhausting until the degree of vacuum in the vacuum chamber is 1×10 ^-5 Torr or less, argon (Ar) gas is introduced to replace the atmospheric gas in the vacuum chamber with Ar gas, and then a high frequency is applied to the target base material, The raw material is plasmatized, and a coating layer is formed on the surface of the oxide glass on which the intermediate layer is formed. The film thickness of the coating layer can be controlled to a desired film thickness by adjusting the pressure (vacuum degree) in the vacuum chamber, the power supply, and the deposition time. In addition, the coating layer should just cover at least a part of the surface of an oxide glass. About this, as mentioned above.

As long as the coating layer is a metal oxide film in a state where oxygen is deficient in comparison with the stoichiometric composition, the metal constituting the metal oxide is not particularly limited. Specific examples of the metal constituting the coating layer include zirconium, yttrium, tantalum, niobium, and tungsten. However, metals not illustrated here may be used. In addition, in this invention, a metal is used in the meaning of including the substance classified as a semimetal. For example, as an example, silicon (Si) is also included in the metal in the present invention.

In order to efficiently accommodate oxygen from the oxide glass, the film thickness of the coating layer is preferably 0.5 nm or more, and more preferably 1.5 nm or more. On the other hand, from the viewpoint of preventing blurring, the film thickness of the coating layer is preferably 15 nm or less, and more preferably 10 nm or less.

As described above, the coating layer described above is in a state deficient in oxygen compared to the stoichiometric composition. For example, in the case of zirconium oxide, the stoichiometric composition is ZrO ₂ , so when the coating layer is a zirconium oxide film, the composition is ZrOx (x<2). Here, as long as x is less than 2, it will not specifically limit. The same applies to other metal oxide films.

<Intermediate Layer>

The intermediate layer is provided between the coating layer and the oxide glass. It should be noted that the glass blank for press molding only needs to have a coating layer on at least a part of the surface of the oxide glass via an intermediate layer, and a part of the surface of the oxide glass may have a part only covered by the intermediate layer, or it may be There are parts covered only by the coating layer. At a temperature equal to or higher than the glass transition temperature of the oxide glass, in the intermediate layer, the diffusion rate (T1) of oxygen atoms contained in the oxide glass is higher than the diffusion rate (T1) of metal atoms contained in the metal oxide film (coating layer). Speed (T2) is fast. In this way, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the material and film thickness of the intermediate layer are not limited as long as the relationship of T1>T2 is satisfied in the intermediate layer. For example, the intermediate layer may be formed using a compound of one or more metal elements and one or more elements selected from the group consisting of oxygen, nitrogen, carbon, and fluorine. The intermediate layer is, for example, a metal oxide film, and examples of the metal oxide film include oxide films of zirconium, yttrium, scandium, and lanthanoid elements. Examples of the lanthanoid elements include lanthanum, cerium, praseodymium, samarium, and ytterbium. These are merely examples, and are not limited to the above-mentioned materials. The film thickness of the intermediate layer may be in the range of, for example, 1 to 15 nm, and the film thickness may be outside this range as long as the relationship of T1>T2 is satisfied at a temperature equal to or higher than the glass transition temperature of the oxide glass. It should be noted that the intermediate layer may be a single layer or a multi-layer structure of two or more layers. In the case of a multilayer structure, the film thickness of the above-mentioned intermediate layer refers to the total film thickness of the multiple layers. The intermediate layer of the multilayer structure only needs to satisfy the relationship of T1>T2 as a whole of the multilayer structure.

As a film formation method of the intermediate layer, a known film formation method such as sputtering and vacuum deposition can be used. For example, the intermediate layer can be formed on at least a part of the surface of the oxide glass by a sputtering method using argon gas. By appropriately performing preliminary experiments, the film-forming conditions for forming the intermediate layer satisfying the relationship of T1>T2 can be determined. For example, a preliminary experiment is performed to prepare a glass blank for test press molding, and after the test press is performed, it is confirmed that there is no significant reduction in the film thickness of the coating layer or disappearance of the film, and the film forming conditions can be used as the actual forming conditions. The film forming conditions of the intermediate layer of the glass blank for press molding used in the press molding.

<Oxide glass>

As the oxide glass, optical glasses of various compositions which are generally used in the production of optical elements can be mentioned. As a specific aspect of such an optical glass, boric acid-rare earth metal-based glass such as borate lanthanum glass, phosphate glass, and silicate glass can be mentioned.

However, among optical glasses, as a composition having a high tendency to foam by molding, there are many compositions containing Nb ₂ O ₅ , TiO ₂ , WO ₃ , and Ta ₂ O ₅ which are high refractive index imparting components. oxide glass. The reason for this is considered to be that these metal oxides are easily reduced compared with other metal oxides under conditions of a glass transition temperature or higher. In the method for producing a glass optical element according to an aspect of the present invention, for example, the above-mentioned intermediate layer and coating layer can be provided on an oxide glass containing at least one selected from Nb ₂ , followed by press-molding. High refractive index imparting components in the group consisting of O ₅ , TiO ₂ , WO ₃ and Ta ₂ O ₅ , and total content of high refractive index imparting components (Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ ) It is 10 mass % or more. As a result, the generation of air bubbles after molding is suppressed and a homogeneous optical element can be obtained. The total content (Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ ) is more preferably 15% by mass or more. In addition, the total content (NbO ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ ) is preferably 50% by mass or less, more preferably 45% by mass or less.

Since the molding temperature is usually performed at a temperature equal to or higher than the glass transition temperature of the oxide glass, the higher the glass transition temperature, the higher the molding temperature tends to be. On the other hand, a significant rise in the molding temperature sometimes contributes to the generation of air bubbles. Therefore, as a preferable specific aspect of an oxide glass, the glass component which contains an appropriate amount of 1 or more types which have the effect|action of lowering a glass transition temperature can be mentioned. As a glass component which has the effect of lowering a glass transition temperature, ZnO and an alkali metal _oxide selected from the group which consists of _Li2O , Na2O, and _K2O are mentioned. The total content of ZnO and alkali metal oxides (ZnO+Li ₂ O+Na ₂ O+K ₂ O) is preferably 5% by mass or more, and more preferably 10% by mass or more. On the other hand, from the viewpoint of ease of vitrification, the total content (ZnO+ _{Li2O +} Na2O ₊ K2O) is preferably 25% by mass or less, more preferably 20% by mass or less. As the oxide glass, from the viewpoint of the usefulness of an optical element, an optical glass having a refractive index nd of 1.70 to 2.10 and an Abbe number νd of 20 to 55 can be exemplified as a specific embodiment. In addition, as another specific aspect, optical glass satisfying either or both conditions of a glass transition temperature of 630° C. or lower and a relaxation temperature of 680° C. or lower can be exemplified as press formability, especially precision press formability. Excellent glass. However, the manufacturing method of the optical element which concerns on one aspect of this invention is not limited to the said specific aspect.

As a more specific aspect of the optical glass which can be an oxide glass, the following glass I, II, and III are mentioned, for example. However, the composition of the oxide glass is not particularly limited. Glasses I, II, and III are all suitable as optical glasses for producing glass optical elements. According to one aspect of the present invention, such optical glass is press-molded to provide a high-quality glass optical element without air bubbles in the glass.

(Glass I)

An oxide glass, which is the following oxide glass:

Expressed in cation %,

A total of 5 to 60% of B ³⁺ and Si ⁴⁺ are contained (wherein, B ³⁺ is 5 to 50%),

5% or more of Zn ²⁺ and Mg ²⁺ in total,

In total, 10 to 50% of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ ,

Totally contains 6 to 45% of Ti ⁴⁺ , Nb ⁵⁺ , Ta ⁵⁺ , W ⁶⁺ and Bi ³⁺ (wherein the total content of Ti ⁴⁺ and Ta ⁵⁺ exceeds 0% and the content of W ⁶⁺ exceeds 0% 5%),

The cation ratio (Si ⁴⁺ /B ³⁺ ) of the Si ⁴⁺ content to the B ³⁺ content is 0.70 or less,

The cation ratio of the Ta ⁵⁺ content to the total content of Ti ⁴⁺ and Ta ⁵⁺ (Ta ⁵⁺ /(Ti ⁴⁺ +Ta ⁵⁺ )) is 0.23 or more,

The cation ratio of the content of W ⁶⁺ to the total content of Nb ⁵⁺ and W ⁶⁺ (W ⁶⁺ /(Nb ⁵⁺ +W ⁶⁺ )) is 0.30 or more,

The cation ratio of the total content of Ti ⁴⁺ , Nb ⁵⁺ , Ta ⁵⁺ , W ⁶⁺ and Bi ³⁺ relative to the total content of B ³⁺ and Si ⁴⁺ ((Ti ⁴⁺ +Nb ^{5 +} +Ta ⁵⁺ +W ⁶⁺ +Bi ³⁺ )/(B ³⁺ +Si ⁴⁺ )) is more than 0.37 and 3.00 or less,

The cation ratio of the total content of Zn ²⁺ , Mg ²⁺ and Li ⁺ relative to the total content of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ ((Zn ²⁺ +Mg ²⁺ +Li ⁺ )/ (La ³⁺ +Gd ³⁺ +Y ³⁺ +Yb ³⁺ )) is 0.40 or more,

The refractive index nd is 1.90 to 2.00, and the Abbe number νd satisfies the following formula (1),

25≤νd<(3.91-nd)/0.06...(1).

Although glass I is a high-refractive-index glass, it exhibits a low glass transition temperature, so it is suitable as a glass for precision press molding. In a preferred embodiment, the glass transition temperature is 650°C or lower. Optical glass with a glass transition temperature of 650°C or lower can maintain the temperature of the glass during precision press molding in a low temperature range, suppress the reaction between the glass and the press molding surface during press molding, and maintain good precision press formability. status. From the above viewpoints, the glass transition temperature is preferably 640°C or lower, more preferably 630°C or lower, still more preferably 620°C or lower, still more preferably 610°C or lower, and still more preferably 600°C or lower.

In addition, when the glass transition temperature is lowered too much, the stability of the glass tends to decrease or the refractive index tends to decrease. Therefore, the glass transition temperature is preferably 500°C or higher, more preferably 520°C or higher, and more preferably It is 540 degreeC or more, More preferably, it is 560 degreeC or more, More preferably, it is 570 degreeC or more.

(Glass II)

An oxide glass, which is the following oxide glass:

Containing B ₂ O ₃ , La ₂ O ₃ and ZnO, expressed in mol%, containing B ₂ O ₃ 20-60%, SiO ₂ 0-20%, ZnO 22-42%, La ₂ O ₃ 5-24%, Gd ₂ O ₃ 0-20% (however, the total amount of La ₂ O ₃ and Gd ₂ O ₃ is 10-24%), ZrO ₂ 0-10%, Ta ₂ O ₅ 0-10%, WO ₃ 0- 10%, Nb ₂ O ₅ 0-10%, TiO ₂ 0-10%, Bi ₂ O ₃ 0-10%, GeO ₂ 0-10%, Ga ₂ O ₃ 0-10%, Al ₂ O ₃ 0-10% 10%, 0 to 10% of BaO, 0 to 10% of Y ₂ O ₃ , and 0 to 10% of Yb ₂ O ₃ , the Abbe number (νd) is 40 or more, and substantially no lithium is contained.

The fact that the glass II does not substantially contain lithium means that the introduction amount of Li ₂ O is suppressed to a level at which blurring or weathering that hinders use as an optical element does not occur on the glass surface. Specifically, it means that the content is suppressed to less than 0.5 mol % in terms of the amount of Li ₂ O. As the amount of lithium is reduced, the risk of fogging and weathering can be reduced. Therefore, the amount of Li ₂ O is preferably suppressed to 0.4 mol % or less, more preferably 0.1 mol % or less, and still preferably not introduced.

Glass II is suitable for precision press molding, and from the viewpoint of preventing the consumption of the press molding mold and the damage of the release film formed on the molding surface of the mold, the glass transition temperature is preferably low, and the glass transition temperature is preferably 630° C. below, more preferably 620°C or below. On the other hand, from the viewpoint of preventing fogging and weathering of the glass surface, the amount of lithium in the glass is limited as described above. Therefore, if the glass transition temperature is excessively lowered, the refractive index is lowered, and the stability of the glass is easily lowered. question. Therefore, the glass transition temperature is further preferably 530°C or higher, and still more preferably 540°C or higher.

For details of the glass II, reference can be made to paragraphs 0013 to 0039 of JP 2006-137662 A (the entire contents of which are specifically incorporated herein as disclosure).

(Glass III)

An oxide glass, which is the following oxide glass:

In mol%, it contains 0-20% of SiO ₂ ,

B ₂ O ₃ 5～40%,

SiO ₂ +B ₂ O ₃ =15-50%,

Li ₂ O 0～10%,

ZnO 12～36%,

Among them, 3×Li ₂ O+ZnO≥18%,

La ₂ O ₃ 5～30%,

Gd ₂ O ₃ 0～20%,

Y ₂ O ₃ 0～10%,

La ₂ O ₃ +Gd ₂ O ₃ =10-30%,

La ₂ O ₃ /ΣRE ₂ O ₃ =0.67 to 0.95%,

(wherein, ΣRE ₂ O ₃ =La ₂ O ₃ +Gd ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ +Sc ₂ O ₃ +Lu ₂ O ₃ )

ZrO ₂ 0.5 to 10%,

Ta ₂ O ₅ 1-15%,

WO ₃ 1～20%,

Ta ₂ O ₅ /WO ₃ ≤2.5 (molar ratio),

Nb ₂ O ₅ 0～8%,

TiO ₂ 0～8%, the refractive index nd is 1.87 or more,

The Abbe number νd is 35 or more and less than 40.

Glass III exhibits low-temperature softening properties with a glass transition temperature of 650°C or lower. The more preferable range of the glass transition temperature which glass III has is 640 degreeC or less, More preferably, it is 630 degreeC or less, More preferably, it is 620 degreeC or less, More preferably, it is 610 degreeC. On the other hand, if the glass transition temperature is lowered too much, it becomes difficult to further increase the refractive index and lower the dispersion, and/or the stability and chemical durability of the glass tend to decrease. Therefore, it is desirable to make the glass transition. The temperature is 510°C or higher, preferably 540°C or higher, more preferably 560°C or higher, and still more preferably 580°C or higher.

Further, the preferred range of the relaxation temperature of glass III is 700°C or lower, more preferably 690°C or lower, still more preferably 680°C or lower, still more preferably 670°C or lower, and still more preferably 660°C or lower. When the relaxation temperature is lowered too much, it becomes difficult to further increase the refractive index and lower the dispersion, and/or the stability or chemical durability of the glass tends to decrease. Therefore, the relaxation temperature is preferably 550°C or higher, more preferably 580°C or higher, still more preferably 600°C or higher, and further preferably 620°C or higher.

For details of the glass III, reference can be made to paragraphs 0016 to 0065 of JP 2008-201661 A (the entire contents of which are specifically incorporated herein as disclosure).

(Molding of oxide glass)

Oxide glass is used as the glass material for press molding, and it is molded into a known shape by a known method as a molding method of the glass material for press molding. For the shape and molding method of the oxide glass, for example, reference can be made to the descriptions in paragraphs 0087 to 0106 and Examples of JP 2011-1259 A, and JP 2004-250295 A (the entire contents of which are specifically incorporated herein by reference). Here) paragraphs 0040 to 0044 and the description of the examples.

<optional coating>

The glass blank for press molding which concerns on one Embodiment of this invention can be obtained by performing the film-forming process of forming the above-mentioned intermediate layer and coating layer on the oxide glass demonstrated above. In the glass blank for press molding, one or more layers of coating films may be optionally formed on the above-mentioned coating layers. Such a film is effective for improving the releasability of the glass from the molding die during press molding, and the like.

A carbon-containing film is mentioned as one form of the above-mentioned arbitrary film. The carbon-containing film can provide sufficient smoothness with the molding die before the molding and when the glass blank for molding (hereinafter also referred to as "glass blank") is supplied to the molding die, and the glass blank can be smoothly moved to the molding die When the glass blank is softened and deformed by pressing, it can contribute to the extension of the glass blank on the surface following the deformation of the glass and the extension of the glass blank on the surface of the molding die. Furthermore, when the press-molded body is cooled to a predetermined temperature after the press-pressing, it is useful in that the glass and the surface of the molding die are easily separated and peeled off, and the mold release is facilitated. In addition, laminating a carbon-containing film on the above-mentioned coating layer is also effective in suppressing the occurrence of cracks during press molding.

The carbon-containing film preferably contains carbon as a main component, but may be a film containing components other than carbon, such as a hydrocarbon film. As a film formation method of the carbon-containing film, known film formation methods such as vacuum deposition using a carbon material, sputtering, ion plating, and plasma CVD (Chemical Vapor Deposition) can be used. Alternatively, the carbon-containing film may be formed by thermal decomposition of carbon-containing substances such as hydrocarbons.

[Glass Optical Element, Glass Optical Element Manufacturing Method]

One aspect of the present invention relates to a glass optical element including:

oxide glass;

A coating layer covering at least a part of the surface of the oxide glass, the coating layer being a metal oxide film deficient in oxygen compared to the stoichiometric composition; and

an intermediate layer provided between the oxide glass and the coating layer,

In the intermediate layer, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the diffusion rate of oxygen atoms contained in the oxide glass is higher than the diffusion rate of metal atoms contained in the metal oxide film at the above temperature quick.

By preparing the glass blank for press molding described above, and then performing press molding to obtain a press-molded body, a glass optical element according to one embodiment of the present invention can be obtained as the press-molded body itself; or by subjecting the press-molded body to film formation A glass optical element according to one embodiment of the present invention can be obtained by performing subsequent steps and the like.

Press molding can be performed by a well-known press molding method as a molding method of an optical element. Hereinafter, specific aspects will be described, but the present invention is not limited to the following aspects.

As the molding die used for press molding, a molding die obtained by precision machining of a material having sufficient heat resistance, rigidity, and density can be used. For example, metals such as silicon carbide, silicon nitride, tungsten carbide, aluminum oxide, titanium carbide, and stainless steel; or their surfaces are coated with carbon, heat-resistant metals, precious metal alloys, carbides, nitrides, borides, etc. film material. From the viewpoint of molding the glass blank for press molding into a glass optical element without heat sticking, fogging, scratches, etc., the film covering the molding surface is preferably a film containing carbon. For the carbon-containing film, reference can be made to paragraph 0116 of Japanese Patent Laid-Open No. 2011-1259. As the molding die, a molding die having a carbon-containing mold release film on the molding surface is used, and there are advantages that the smoothness of the molding surface and the glass blank is improved, and the moldability is further improved.

FIG. 3 is a diagram showing an example of a press molding apparatus. At the time of press molding, as shown in FIG. 3 , a press molding glass blank PF in which the oxide glass 1 is covered with the intermediate layer 2 and the coating layer 3 is supplied into the molding die 7 including the upper mold 4 , the lower mold 5 , and the body mold 6 . , raise the temperature to a temperature range suitable for molding.

For example, the heating temperature of the glass blank PF for press molding can be appropriately set according to the type of the oxide glass 1, but it is preferably set in a temperature range where the viscosity of the oxide glass 1 is 10 ⁵ to 10 ¹⁰ dPa·s. Temperature zone for compression molding. For the molding temperature, for example, it is more preferable that the oxide glass 1 is a temperature corresponding to 10 ⁶ to 10 ⁸ dPa·s before and after 10 ^7.2 dPa·s, and more preferably a temperature corresponding to 10 ^7.2 dPa·s for the oxide glass 1 . way to set the temperature. Usually, the pressing temperature is set to a temperature equal to or higher than the glass transition temperature of the oxide glass. At such a temperature, the oxide glass-coated glass for press molding is treated with a coating layer that is a metal oxide film in a state deficient in oxygen compared to the stoichiometric composition, and an intermediate layer satisfying the relationship of T1>T2. The blank is press-molded so that oxygen atoms, which are causes of bubble generation, are accommodated in the metal oxide film, thereby preventing the generation of air bubbles in the press-molded body obtained by press-molding. In addition, the press temperature and the heating temperature related to press molding refer to the temperature of the atmosphere in which press molding is performed. Press molding can be performed by applying a predetermined load to the upper mold 4 .

In the press molding, the glass blank PF for press molding may be supplied to the molding die 7, and both the glass blank PF for press molding and the molding die 7 may be heated to a predetermined range; or the glass blank PF for press molding and the molding die 7 may be separately After the temperature is raised to a predetermined temperature range, the glass blank PF for press molding is placed in the molding die 7 . Furthermore, a method of raising the temperature of the glass blank PF for press molding to a temperature corresponding to a viscosity of 10 ⁵ to 10 ⁹ dPa·s, and raising the temperature of the molding die 6 to a temperature corresponding to a viscosity of the glass of 10 ⁹ to 10 ¹² dPa·s temperature, the press-molding glass blank PF is placed in the molding die 7, and press-molding is performed immediately. At this time, since the temperature of the molding die can be relatively lowered, there are effects that the heating/cooling cycle of the molding apparatus can be shortened and the deterioration due to the heat of the molding die 7 can be suppressed. In either case, cooling is started at or after the start of press molding, and the temperature is lowered while applying an appropriate load application schedule while maintaining the close contact between the molding surface and the glass blank PF. After that, mold release is performed, and the press-molded body is taken out. The demolding temperature is preferably performed in a form corresponding to 10 ^12.5 to 10 ^13.5 dPa·s.

In one embodiment, a coating layer (metal oxide film) provided in the press-molding glass blank PF exists in the press-molded body after mold release, and oxygen atoms are contained in the oxide glass, so that the oxygen content ratio is higher than that of press-molding A high coating layer before molding, that is, a metal oxide film having a higher content ratio of oxygen atoms to metal atoms than the coating layer of the glass blank for press molding before press molding. In one form, the metal oxide film is in a state deficient in oxygen compared to the stoichiometric composition. Moreover, in one form, the press-molded body after press-molding includes oxide glass, a coating layer covering at least a part of the surface of the oxide glass, and an intermediate layer provided between the oxide glass and the coating layer. Here, in one form, the above-mentioned coating layer included in the press-molded body is a metal oxide film in a state of being deficient in oxygen compared to the stoichiometric composition. In one embodiment, in the intermediate layer included in the press-molded body, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the diffusion rate of oxygen atoms contained in the oxide glass is higher than that of the metal at the temperature. The diffusion rate of metal atoms contained in the oxide film is high.

However, various forms other than the above-mentioned forms are also included in the present invention as one form of the present invention.

The molded body after compression molding can be shipped directly as the final product, that is, the optical element; or the final product can be obtained after subsequent processing such as centering processing or film forming treatment of optically functional films such as anti-reflection films on the surface. . For example, on a press-molded body having the above-described coating layer after press-molding, a film of materials such as Al ₂ O ₃ , ZrO ₂ -TiO ₂ , MgF ₂ and the like can be appropriately formed in a single-layer or laminated form to form a film. Desired anti-reflection film. The film-forming method of the antireflection film can be performed by a known method such as a vapor deposition method, an ion-assisted vapor deposition method, an ion plating method, and a sputtering method. For example, in the case of the vapor deposition method, a vapor deposition apparatus is used to heat the vapor deposition material by an electron beam, direct energization, or arc in a vacuum atmosphere of about 10 ^-4 Torr, and the material produced from the evaporation and sublimation of the material is produced. The vapor is transported to the substrate to be condensed/precipitated, so that an anti-reflection film can be formed. The heating temperature of the press-molded body can be set to about room temperature to 400°C. However, when the glass transition temperature of the oxide glass constituting the press-molded body is 450°C or lower, the upper limit temperature for heating the press-molded body is preferably glass transition temperature -50°C.

The optical element of one embodiment of the present invention may be a small-diameter, thin-walled, low-mass lens, such as a small imaging lens mounted on a camcorder, a communication lens, an objective lens for optical pickup, a collimator lens, and the like. The lens shape is not particularly limited, and various shapes such as a convex meniscus lens, a concave meniscus lens, a biconvex lens, and a biconcave lens may be used.

Example

The present invention will be further described below based on examples. However, the present invention is not limited to the modes shown in the embodiments.

The glass transition temperature and the sag temperature described below are values measured with a thermomechanical analyzer of Rigaku Electric Co., Ltd. at a temperature increase rate of 4° C./min.

The refractive index nd and the Abbe number νd were measured with respect to the optical glass obtained by setting the slow cooling rate to -30°C/hour.

1. Production of glass blanks for press molding and production of optical components

[Comparative Example 1]

(1) Production of glass blanks for press molding

As the oxide glass of the glass blank for press molding, the optical glass III-1 described in Table 1 belonging to the above-mentioned glass III was used.

First, the oxide glass is dropped in a molten state into a storage mold, cooled, and preformed into a glass block having a convex shape on one surface and the other surface. For the preformed glass block, a ZrO ₂ film (film thickness: about 5 nm) and a SiO ₂ film ( Film thickness: about 5 nm) was sequentially formed into a film to obtain a glass blank for press molding. The outer dimension of the obtained glass blank for press molding was 17-18 mm, and the wall thickness of the center part was 7-8 mm.

【Table 1】

(unit: mass %)

Glass III-1 SiO₂ 0.6 B₂O₃ 14.9 ZnO 15.7 La₂O₃ 31.0 Gd₂O₃ 10.1 ZrO₂ 3.5 Ta₂O₅ 12.4 WO₃ 11.8 Sb₂O₃ 0.02 glass transition temperature 604℃ sag temperature 643℃ Refractive index nd 1.88202 Abbe number νd 37.22

(2) Production of press-molded body by precision press molding

的双凸形状的非球面玻璃透镜。Next, the glass blank for press molding produced in the above (1) was press-molded by a precision press-molding apparatus in a nitrogen atmosphere. That is, using a molding die composed of an upper and lower mold made of SiC and a body mold on which a carbon-containing release film by sputtering is formed on the molding surface, the atmosphere in the chamber of the molding apparatus is filled with non-oxidizing N ₂ gas , then heated to a temperature at which the viscosity of the oxide glass is 10 ^7.2 dPa·s, and supplied to a molding die heated to a temperature equivalent to 10 ^8.5 dPa·s by the viscometer of the oxide glass. Immediately after the supply, the press-molding glass blank is pressed between the upper and lower molds (molding temperature 675°C), and the glass blank for press-molding is cooled to the slow cooling temperature of the oxide glass while maintaining the close contact between the press-molding glass blank and the upper and lower molds. At the following temperature, the press-molded body was taken out from the molding die. The outer diameter of the press-molded body was 26.0 mm, and the central wall thickness was 4.0 mm. Next, the outer peripheral portion of the press-molded body was centered by grinding to obtain

biconvex shaped aspheric glass lens.

[Example 1]

In place of the SiO ₂ film of Comparative Example 1, a zirconium oxide film (film thickness: about 5 nm) was formed as a coating layer on the ZrO ₂ film. In the film formation, metal zirconium (Zr) was used as a target, and the film was formed by a sputtering method at a film formation temperature of 300° C. in an atmosphere of 100% Ar, and the film thickness was adjusted according to the sputtering conditions. A ZrO ₂ film as an intermediate layer was directly formed on the oxide glass. In addition, the zirconium oxide film as the coating film was directly formed on the ZrO ₂ film as the intermediate layer.

The thus obtained glass blank for press molding has a zirconium oxide film as a coating layer and a ZrO ₂ film as an intermediate layer. Using this glass blank for press molding, an aspherical glass lens was obtained by the same method as above.

[Example 2]

A glass blank for press molding was obtained in the same manner as in Example 1, except that metal yttrium (Y) was used instead of metal zirconium, and a coating layer having a thickness of about 5 nm was formed.

Using the thus obtained glass blank for press molding, an aspherical glass lens was obtained by the same method as described above.

[Comparative Example 2]

A glass blank for press molding was obtained in the same manner as in Example 2 except that the intermediate layer was not formed.

Using the thus obtained glass blank for press molding, an aspherical glass lens was obtained by the same method as described above.

[Example 3]

A glass blank for press molding was obtained in the same manner as in Example 1, except that metal tantalum (Ta) was used instead of metal zirconium, and a coating layer having a thickness of about 5 nm was formed.

Using the thus obtained glass blank for press molding, an aspherical glass lens was obtained by the same method as described above.

[Example 4]

A glass blank for press molding was obtained in the same manner as in Example 1, except that metal niobium (Nb) was used instead of metal zirconium, and a coating layer having a thickness of about 5 nm was formed.

Using the thus obtained glass blank for press molding, an aspherical glass lens was obtained by the same method as described above.

[Example 5]

A glass blank for press molding was obtained in the same manner as in Example 1, except that metal tungsten (W) was used instead of metal zirconium, and a coating layer having a thickness of about 5 nm was formed.

Using the thus obtained glass blank for press molding, an aspherical glass lens was obtained by the same method as described above.

[Example 6]

A glass blank for press molding was obtained in the same manner as in Example 1, except that metal titanium (Ti) was used instead of metal zirconium, and a coating layer having a thickness of about 5 nm was formed.

Using the thus obtained glass blank for press molding, an aspherical glass lens was obtained by the same method as described above.

[Comparative Example 3]

A glass blank for press molding was obtained in the same manner as in Example 1, except that Y ₂ O ₃ was used instead of metal zirconium, and a Y ₂ O ₃ film having a thickness of about 5 nm was formed as a coating layer.

Using the thus obtained glass blank for press molding, an aspherical glass lens was obtained by the same method as described above.

2. Appearance evaluation of optical components

When observed with an optical microscope at a magnification of 10 to 50 times, less than one bubble with a diameter of 50 μm or more, less than two bubbles with a diameter of 25 μm or more, or less than 5 bubbles with a diameter of 10 μm or more, In addition, the case where the total diameter of the bubbles does not exceed 50 μm is used as an index (hereinafter referred to as “appearance index 1”) of a homogeneous optical element with suppressed generation of bubbles.

More preferably, when observed with an optical microscope at a magnification of 10 to 50 times, less than one bubble with a diameter of 25 μm or more, or less than three bubbles with a diameter of 10 μm or more, and the total diameter of the bubbles can be determined. The case where it does not exceed 25 μm is used as an index of a bubble-free and homogeneous optical element (hereinafter referred to as “appearance index 2”).

Here, the total of the bubble diameters means that, for example, if two bubbles with a diameter of 50 μm exist, the total of the bubble diameters is 100 μm. In addition, the diameter here refers to the diameter when the bubbles are circular bubbles, refers to the distance in the long axis direction when the bubbles are elliptical bubbles, and refers to the distance in the long axis direction when the bubbles are amorphous bubbles Take the longest distance.

The lenses produced in the Examples and Comparative Examples were observed with an optical microscope at a magnification of 50 times, and the appearance index 1 and the appearance index 2 were evaluated. About each appearance index, the case where it is satisfied is marked with ○, and the case where it is not satisfied is marked with ×, and the results are shown in Table 2.

【Table 2】

As shown in Table 2, in Examples 1 to 6, the appearance indexes 1 and 2 were both ○, but the appearance indexes 1 and 2 of Comparative Examples 1 to 3 were both ×.

The coating layers of Examples 1 to 6 are metal oxide films formed by using a metal element in a non-oxidizing atmosphere, and thus are in a state of oxygen deficiency compared with the stoichiometric composition. In contrast, the coating layer of Comparative Example 1 is in a state of being deficient in oxygen. It is a SiO ₂ film described in Japanese Patent Laid-Open No. 2011-1259, that is, a silicon oxide film with a stoichiometric composition.

In addition, Comparative Example 2 differs from Example 2 in the presence or absence of an intermediate layer.

Details will be described later, but the coating layer of Comparative Example 3 is a yttrium oxide film having a stoichiometric composition, that is, a Y ₂ O ₃ film.

In addition, in Examples 1-6, it was confirmed from the observation result by an optical microscope etc. that the film thickness of a coating layer before and after press-pressing was not significantly reduced or the film disappeared. From this result, it was confirmed that the intermediate layers of Examples 1 to 6 satisfy the relationship of T1>T2.

As shown in Table 2, it was confirmed that Examples 1 to 6 were excellent in the evaluation results of appearance evaluation compared with Comparative Examples 1 to 3. Therefore, it was confirmed that the metal oxide films in the oxygen-deficient state compared with the stoichiometric composition were By being provided on the oxide glass through an intermediate layer satisfying T1>T2, it is possible to suppress the generation of air bubbles inside the glass during press molding.

3. Confirmation of gas composition in bubbles

The gas composition in the bubbles in the lens produced in Comparative Example 1 was analyzed by mass spectrometry, and as a result, even when press-molding was performed in a nitrogen atmosphere, more than 10% of oxygen was detected. This result can prove that the oxygen derived from the oxide glass is the cause of the bubble generation as described above.

In Comparative Example 1, the coating layer was a SiO ₂ film of stoichiometric composition. Since such a metal oxide film is chemically stable, it is considered that oxygen derived from oxide glass cannot be contained in the film during press molding. As a result, it is presumed that foaming occurs in the glass.

4. Analysis based on TOF-SIMS (1)

The glass blank and optical element for press molding produced under the same conditions as in Example 1 were subjected to TOF-SIMS (Time-of-flight secondary ion mass spectrometer) by the following method. Compositional analysis in the depth direction from the surface.

Depth direction analysis based on TOF-SIMS

The depth direction measurement was carried out using TOF-SIMS300 manufactured by ION-TOF Corporation. TOF-SIMS is a method of irradiating pulsed primary ions and detecting the generated secondary ions. In the depth direction analysis by TOF-SIMS, the following (i) to (iii) are repeated: (i) irradiation of primary ions, (ii) measurement of generated secondary ions, and (iii) irradiation of sputtered ions, thereby Get data.

Bi ₃ ⁺⁺ was used as the primary ion source, and the voltage applied to the column of the primary ion source was 25 kV. The measurement was performed with the current of the primary ion source set to 0.2 pA. The irradiation area of the primary ion source (=measurement area for detecting secondary ions) was 100 μm square, and the secondary ions were detected as negative ions.

The sputter ion source uses Cs. The acceleration of the sputtering ion source was adjusted under the conditions of 1 kV and a current value of 75.4 nA. The sputtering was performed under the condition that the area of the sputtering ion source was 400 μm square.

4 is a graph showing the result of a depth-direction analysis of secondary ion strength by TOF-SIMS before press molding (glass blank for press molding) in Example 1. FIG.

In Example 1, the film thicknesses of the zirconium oxide film formed as the coating layer and the ZrO ₂ film formed as the intermediate layer on the oxide glass were both about 5 nm. In FIG. 4 , ZrO ₂ and elemental Zr (“Zr” in FIG. 4 ) are described as secondary ions derived from the zirconium oxide film and the ZrO ₂ film. In addition, although omitted in FIG. 4 , ZrO derived from the zirconium oxide film and the ZrO ₂ film was also detected. Since Zr ₂ was not detected, it is considered that elemental Zr is not derived from metal Zr, but is derived from the zirconium oxide film and the ZrO ₂ film.

In FIG. 4 , peaks exist in the spectrum of ZrO ₂ in the region from the surface (depth 0 nm) to the depth of about 5 nm and the region from the depth of about 5 nm to about 10 nm, respectively, and the oxide glass origin is detected in the region after the depth of about 10 nm. Therefore, it was confirmed that _two layers, an intermediate layer provided on the oxide glass and a coating layer provided on the intermediate layer were formed.

In the depth direction analysis result of secondary ion intensity by TOF-SIMS after compression molding (optical element), in the region from the surface (depth 0 nm) to the depth of about 10 nm, ZrO ₂ The peak intensity is high, and WO ₃ is detected in a region after a depth of about 10 nm. From this result, it was confirmed that the coating layer was present on the oxide glass without a significant reduction in film thickness or disappearance of the film even after press molding. From this result, it can also be confirmed that the intermediate layer satisfies the relationship of T1>T2.

The secondary ionic strength of ZrO ₂ /Zr was determined from the results of depth-direction analysis of the secondary ionic strength by TOF-SIMS before press molding (glass blank for press molding) and after press molding (optical element) in Example 1. ratio (hereinafter referred to as "ZrO ₂ /Zr intensity ratio"). The ZrO ₂ /Zr intensity ratio is an index indicating the degree of oxidation in the zirconium oxide film. When the zirconium oxide is in a state deficient in oxygen compared to the stoichiometric composition, the ZrO ₂ /Zr intensity ratio is smaller than that of the stoichiometric composition, that is, ZrO ₂ .

From the results obtained before press molding (glass blank for press molding), it was confirmed that the ZrO ₂ /Zr strength ratio was lower than that of ZrO ₂ in a region corresponding to the coating layer. From this result, it was confirmed that the zirconium oxide film serving as the coating layer of the glass blank for press molding of Example 1 was in a state of being deficient in oxygen compared to the stoichiometric composition.

In addition, in the region corresponding to the coating layer, it was confirmed that the ZrO ₂ /Zr strength ratio became larger after the compression molding than before the compression molding. That is, it was confirmed that the oxygen content of the coating layer increased after press molding. The present inventors considered that this result indicates that the coating layer accommodated oxygen from the oxide glass.

5. Analysis based on TOF-SIMS (2)

About the glass blanks for press molding and the optical element produced under the same conditions as Example 2 and Comparative Example 3, the composition analysis of the depth direction from the surface was performed by the method similar to the above 4. by TOF-SIMS.

FIG. 5 is a diagram showing the result of a depth-direction analysis of the secondary ion intensity by TOF-SIMS before press molding (glass blank for press molding) in Example 2. FIG.

In Example 2, the film thicknesses of the yttrium oxide film formed as the coating layer and the ZrO ₂ film formed as the intermediate layer on the oxide glass were both about 5 nm. In FIG. 5 , YO ₂ and YO are described as secondary ions derived from the yttrium oxide film. In addition, although omitted in FIG. 5 , the elemental Y was detected in a small amount. On the other hand, since Y ₂ was not detected, it is considered that the elemental Y is not derived from the metal Y but is derived from the yttrium oxide film.

In FIG. 5 , the peaks of the spectrum of YO ₂ and YO exist in the region from the surface (depth 0 nm) to the depth of about 5 nm, the spectrum of ZrO ₂ has peaks in the region of the depth of about 5 nm to about 10 nm, and the region after the depth of about 10 nm Since WO ₃ derived from the oxide glass was detected, it was confirmed that two layers of an intermediate layer (ZrO ₂ film) provided on the oxide glass and a coating layer (yttrium oxide film) provided on the intermediate layer were formed.

In the depth direction analysis result of secondary ion intensity by TOF-SIMS after compression molding (optical element), the peaks of the spectrum of YO ₂ and YO exist in the region from the surface (depth 0 nm) to the depth of about 5 nm. The spectrum of ZrO ₂ has a peak in the region of 5 nm to about 10 nm, and WO ₃ derived from oxide glass is detected in the region of about 10 nm in depth. From this result, it was confirmed that the coating layer was present on the oxide glass without a significant reduction in film thickness or disappearance of the film even after press molding. From this result, it can also be confirmed that the intermediate layer satisfies the relationship of T1>T2.

For Example 2 and Comparative Example 3, from the results of the depth direction analysis of the secondary ion intensity by TOF-SIMS before compression molding (glass blank for compression molding) and after compression molding (optical element), the values before compression molding and Secondary ion intensity ratios of YO ₂ /YO at positions of 2.5 nm, 3.0 nm, 3.5 nm, and 4.0 nm in depth from the surface after compression molding (hereinafter referred to as "YO ₂ /YO intensity ratio"). The results obtained for Example 2 are shown in Table 3, and the results obtained for Comparative Example 3 are shown in Table 4.

【table 3】

【Table 4】

The YO ₂ /YO intensity ratio is an index indicating the degree of oxidation in the yttrium oxide film. When the yttrium oxide is in a state deficient in oxygen compared to the stoichiometric composition, the YO ₂ /YO intensity ratio is smaller than that of the stoichiometric composition, that is, Y ₂ O ₃ . From the YO ₂ /YO intensity ratios shown in Tables 3 and 4, the following can be confirmed.

The YO ₂ /YO intensity ratio at each position of the coating layer of Comparative Example 3 before press molding shown in Table 4 is the same as the YO ₂ /YO intensity ratio of yttrium oxide with a stoichiometric composition, that is, Y ₂ O ₃ . From this result, it was confirmed that the coating layer of Comparative Example 3 was an yttrium oxide film having a stoichiometric composition, that is, a Y ₂ O ₃ film.

On the other hand, the YO ₂ /YO intensity ratio at each position of the coating layer of Example 2 before press molding shown in Table 3 is higher than the YO ₂ /YO intensity ratio of the stoichiometric composition of yttrium oxide (Y ₂ O ₃ ). Small. From this result, it was confirmed that the yttrium oxide film as the coating layer of the glass blank for press molding of Example 2 was in a state where oxygen was deficient in comparison with the stoichiometric composition.

In addition, as shown in Table 3, in the coating layer of Example 2, the YO ₂ /YO intensity ratio became larger after the compression molding at each position than before the compression molding. That is, it was confirmed that the oxygen content of the coating layer increased after the press molding. The present inventors consider this result to be a result indicating that the coating layer accommodated oxygen from the oxide glass. However, the YO 2 /YO intensity ratio at each position after the compression molding of the coating layer of Example ₂ is smaller than the YO ₂ /YO intensity ratio of the stoichiometric composition of yttrium oxide (Y ₂ O ₃ ). From this result, it was confirmed that the coating layer of Example 2 was also in a state of being deficient in oxygen compared with the stoichiometric composition after the press molding.

In contrast, as shown in Table 4, in the coating layer of Comparative Example 3, no significant difference was observed in the YO ₂ /YO strength ratio before and after compression molding at each position. As described above, the coating layer of the press-molding glass blank of Comparative Example 3 was a Y ₂ O ₃ film having a stoichiometric composition. Since such a metal oxide film is chemically stable, it is considered that oxygen derived from oxide glass cannot be contained in the film during press molding. The reason for this is presumed to be that, as shown in Table 4, no significant difference in the YO ₂ /YO strength ratio was observed before and after compression molding.

It should be noted that in the examples, a metal oxide film as an intermediate layer was formed, and more specifically, a zirconium oxide film was formed, but the intermediate layer only needs to satisfy the relationship of T1>T2, and is not limited to those shown in the examples. Way.

Finally, the above methods are summarized.

According to one aspect, there is provided a glass optical element having:

oxide glass;

A coating layer covering at least a part of the surface of the oxide glass, the coating layer being a metal oxide film deficient in oxygen compared to the stoichiometric composition; and

an intermediate layer provided between the oxide glass and the coating layer,

In the intermediate layer, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the diffusion rate of oxygen atoms contained in the oxide glass is higher than the diffusion rate of metal atoms contained in the metal oxide film at the above temperature quick.

According to one aspect, there is provided a glass blank for press molding, which includes:

oxide glass;

A coating layer covering at least a part of the surface of the oxide glass, the coating layer being a metal oxide film deficient in oxygen compared to the stoichiometric composition; and

an intermediate layer provided between the oxide glass and the coating layer,

In the intermediate layer, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the diffusion rate of oxygen atoms contained in the oxide glass is higher than the diffusion rate of metal atoms contained in the metal oxide film at the above temperature quick.

According to one aspect, there is provided a method for producing a glass optical element including a press-molding step of press-molding a glass blank for press-molding to form a press-molded body,

The said glass blank for press-molding is the glass blank for said press-molding.

According to the manufacturing method of the optical element using the glass blank for press molding mentioned above, the generation|occurence|production of a bubble is suppressed and the optical element which is homogeneous can be provided.

In one form, the glass optical element obtained by the said manufacturing method is provided.

Additionally, in one approach,

In the above-mentioned manufacturing method of an optical element,

The above-mentioned press-molded body includes the above-mentioned coating layer subjected to the above-mentioned press-forming process, and,

The coating layer after the pressing step is a metal oxide film having a higher oxygen content than the coating layer before the pressing step.

Moreover, in one form, the metal oxide film with which the said press-molded body is equipped is in the state which is deficient in oxygen compared with a stoichiometric composition.

In addition, the press-molded body after press-molding includes the case where it is directly applied to an imaging camera as an optical element, and the case where it is used as an optical element after removing its end through a centering process. In the latter case, the above-mentioned coating layer (metal oxide film) is partially removed by the centering process.

In one embodiment, the oxide glass contains one or more high refractive index imparting components selected from the group consisting of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Ta ₂ O ₅ . The total content (Nb ₂ O ₅ +TiO ₂ +WO ₃ +Ta ₂ O ₅ ) of the high refractive index imparting components is preferably 10% by mass or more and 50% by mass or less.

In one embodiment, the oxide glass contains ZnO and at least one selected from the group consisting of alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O). Preferably, the total content of ZnO and alkali metal oxides (ZnO+Li ₂ O+Na ₂ O+K ₂ O) is 5 mass % or more and 25 mass % or less.

In one form, the heating during press molding is performed at a heating temperature of 650° C. or higher. According to the manufacturing method of the optical element described above, the generation of air bubbles in the press molding at such a high temperature can be suppressed.

It should be understood that the embodiments disclosed this time are illustrative in all respects, and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that the meanings equivalent to the claims and all modifications within the scope are included.

The present invention is useful in the field of manufacture of optical elements such as glass lenses.

Claims (7)

1. A glass optical element comprising:

oxide glass;

a coating layer that coats at least a part of a surface of the oxide glass, the coating layer being a metal oxide film that is deficient in oxygen compared with a stoichiometric composition; and

an intermediate layer provided between the oxide glass and the coating layer,

in the intermediate layer, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the oxygen atoms contained in the oxide glass diffuse at a higher rate than the metal atoms contained in the metal oxide film at the temperature,

the metal oxide is an oxide of a metal selected from the group consisting of zirconium, yttrium, tantalum, niobium, tungsten, and titanium.

2. The glass optical element according to claim 1, wherein the intermediate layer is a metal oxide film.

3. The glass optical element according to claim 2, wherein the intermediate layer is a zirconium oxide film.

4. A glass material for press molding, comprising:

oxide glass;

a coating layer that coats at least a part of a surface of the oxide glass, the coating layer being a metal oxide film that is deficient in oxygen compared with a stoichiometric composition; and

an intermediate layer provided between the oxide glass and the coating layer,

in the intermediate layer, at a temperature equal to or higher than the glass transition temperature of the oxide glass, the oxygen atoms contained in the oxide glass diffuse at a higher rate than the metal atoms contained in the metal oxide film at the temperature,

the metal oxide is an oxide of a metal selected from the group consisting of zirconium, yttrium, tantalum, niobium, tungsten, and titanium.

5. A press molding glass blank according to claim 4, wherein the intermediate layer is a metal oxide film.

6. A press molding glass blank according to claim 5, wherein the intermediate layer is a zirconium oxide film.

7. A method for manufacturing a glass optical element, comprising a press molding step of press molding a glass material for press molding to form a press molded body,

a press molding glass material according to any one of claims 4 to 6.

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